Records of Holocene climatic fluctuations and anthropogenic lead input in elemental distribution and radiogenic isotopes (Nd and Pb) in sediments of the Gulf of Lions (Southern France) (original) (raw)
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Journal of Environmental Monitoring, 2004
Lead concentrations and isotopic ratios were measured along two well-dated sediment cores from two distant lakes: Anterne (2100 m a.s.l.) and Le Bourget (270 m a.s.l.), submitted to low and high direct human impact and covering the last 250 and 600 years, respectively. The measurement of lead in old sediment samples (w3000 BP) permits, in using mixing-models, the determination of lead concentration, flux and isotopic composition of purely anthropogenic origin. We thus show that since ca. 1800 AD the regional increase in lead contamination was mostly driven by coal consumption (206 Pb/ 207 Pb y 1.17-1.19; 206 Pb/ 204 Pb y 18.3-18.6), which peaks around 1915 AD. The increasing usage of leaded gasoline, introduced in the 1920s, was recorded in both lakes by increasing Pb concentrations and decreasing Pb isotope ratios. A peak around 1970 (206 Pb/ 207 Pb y 1.13-1.16; 206 Pb/ 204 Pb y 17.6-18.0) corresponds to the worldwide recorded leaded gasoline maximum of consumption. The 1973 oil crisis is characterised by a drastic drop of lead fluxes in both lakes (from y35 to v20 mg cm 22 yr 21). In the late 1980s, environmental policies made the Lake Anterne flux drop to pre-1900 values (v10 mg cm 22 yr 21) while Lake Le Bourget is always submitted to an important flux (y25 mg cm 22 yr 21). The good match of our distant records, together and with a previously established series in an ice core from Mont Blanc, 1 provides confidence in the use of sediments as archives of lead contamination. The integration of the Mont Blanc ice core results from Rosman et al. 1 with our data highlights, from 1990 onward, a decoupling in lead sources between the high elevation sites (Lake Anterne and Mont Blanc ice core), submitted to a mixture of long-distance and regional contamination and the low elevation site (Lake Le Bourget), where regional contamination is predominant.
Lead isotope signatures of Holocene fluvial sediments from the Loire River valley
Applied Geochemistry, 2004
The distribution of Mn, V, Th, Pb and isotopes of Pb in the labile fraction of sediments from a channel infill in the Middle Loire alluvial plain are used to highlight some aspects of the basin evolution over the period from 0 to 10 ka BP. The acid extractable matter (AEM) in the sediment samples is variable in amount and in trace element contents. Iron-Mn oxyhydroxides are the principle trace element carrying phase in the labile fraction and carbonates are a secondary carrier. Vanadium and Pb originate from the weathering of silicates and are used as a silicate erosion rate index in the fluviatile record. Most of the AEM data plot along a general trend between 3 endmembers (basalts, Cretaceous carbonate rocks and granites) in the relationship between 207 Pb/ 206 Pb and 206 Pb/ 206 Pb. These endmembers have been mixed in various proportions depending on natural Holocene inputs (erosion, volcanic events) or human influences (mining and smelting of ore). #
Lead concentrations and isotopic compositions were determined on both bulk sediments deposited in the Thau lake in southern France during the last 200 years, and leachates derived from a series of sequential leachings of the sediments, making it possible to identify the sources, natural (i.e. indigenous lithologic) or anthropogenic, and to quantify the dierent inputs of Pb. Two distinct inputs of Pb could be distinguished. One of these corresponds to the terrigenous material entering the basin, representative of the local natural Pb `background'. Its supply remained steady most of the time with 206Pb/207Pb ratios of 1.200 2 0.003, except at the time of heavy storms producing voluminous and sudden depositions, such as that of September 1875. This Pb supply is mainly hosted by the detrital silicate fraction of the sediments. The second Pb input is a direct consequence of anthropogenic activities of various industrial and domestic emissions in the region, particularly due to the city of SeÁte and, to a lesser extent, to the villages in the watershed. The 206Pb/207Pb ratios of this input are of 1.142±1.162. The Pb added to gasoline could also be identi®ed in the uppermost sediments, because of its speci®c 206Pb/207Pb ratios of 1.069±1.094. The leaching experiments also showed that the anthropogenic Pb is mainly hosted by the oxi-hydroxides of the sediments and to a lesser extent by the carbonates. It may also be adsorbed on particle surfaces, while only limited amounts are bound to organic matter.
Radioprotection, 2002
Since heavy metal deposition records are scarced in urbanized areas, we used saltmarsh and marine sediments as proxies to reconstruct heavy metal fluxes during the last century in the Camargue (South France). 2l "Pb, l31 Cs and stable lead were analyzed in order to determine their inventories and to reconstruct temporal trends in concentrations and fluxes in two zones of the coastal environment. Two cores were collected in a saltmarsh environment and another one in the Gulf of Lions continental slope. Regarding the radionuclide profiles, one core from the saltmarsh appears to be influenced by Rhone flooding deposits. The other cores seem to reflect the atmospheric supply. Werner they were collected in different environment (saltmarsh and slope sediments), their pollutant lead inventories are in good agreement. The 210 Pb excess inventories determinate in the same core are also very concomitant, and confirm the level of anthropogenic accumulation.
Six marine sediment cores from the Gulf of Lions continental slope (700–1700 m water depth) were analyzed for stable lead isotopes and 210/Pb geochronology in order to reconstruct lead atmospheric fallout pattern during the last century. The detrital lead contribution is 25 µg.g -1 and the mean sediment anthropogenic inventory is 110 ± 7 g cm-2 , a little bit higher than atmospheric deposition estimate. Anthropogenic lead accumulation in sediments peaked in early 1970s (1973 ± 2) in agreement with lead emissions features. For the period 1986–1997, the sediment signal also reflect the decrease of atmospheric lead described by independent atmospheric fallout investigations. The anthropogenic Pb deposition in the late 1990s was similar to the 1950s deposition, attesting thus of the output of European environmental policies.
Biogeochemical Investigations at Watershed, Landscape, and Regional Scales, 1998
Variations in Pb concentration in lake sediments reflect changes in the fluxes of this element in the• past. A sediment core from a lake in the Pyrenees (Lake Redo at 2,240 m a.s.L, N_E Spain) was studied, with the aim of reconstructing pastenvironmenial and climatic conditions in the lake and its catchment area. The core was dated usii1g both 210 Pb and 14 C. A surface peak of Pb concentration, which was about 10 tim~s higher than the background level, was found. This peak is attributed to mining activities since the begioping of this century. Although Pb pollution due to the combustion of gasoline is expected to be present, no evidence can be deduced from Pb isotope ratios of sediment due to the masking effect of Pb from mines. A second peak appeared in a deeper layer, with a maximum Pb concentration of about 17 times higher than the background level. The origin of this peak is unclear. All evidence suggests that the ancient peak is due to mining operations in the central Pyrenees area, which were not documented historically.
Progress in Oceanography, 2017
The Rhône pro-delta sediments receive the particulate inputs from the Rhône River, the largest freshwater discharge of the Western Mediterranean Sea. Trace element (TEs: Ag, Cd, Co, Cr, Cu, Ni, Pb, and Zn) concentrations and stable Pb isotope ratios were determined along a 7.7-meter-long sediment core collected from the Rhône prodeltaic lobe, archiving the deposits of the last 400 years. Trace element mean concentrations during the pre-industrialized era (before 1850 AD) were no different from the average composition of Earth's upper crust, except for Cr. Principal component analysis, performed on TEs and tracers, suggests three origins for TEs that we identified as (i) marine biogenic material (Ag, Cd), (ii) ultramafic rocks (Li, Cr, Ni), and (iii) other clay minerals (Co, Cu, Pb and Zn). During the pre-industrial period, several changes in the TE/Al ratios coincided with flood events or/and modifications in the channelization of the Rhône River mouth. Some frequencies in the TEs temporal variations allow us to hypothesize some influence of climate variation. Sediments deposited after 1850 AD exhibited concentrations of certain TEs exceeding 1.3 to 3.5 times the concentrations of the preindustrial era (Ag> Cd-Pb>Cu-Zn). Principal component analysis, performed on post-1850 AD data, allows to distinguish pristine and "anthropogenically impacted" TEs. Pristine TEs, such as Co, Cr, and Ni, are linked with clay markers (Al, Li and Fe), Co and Ni are associated with Mn-enrichment, whereas Cr is correlated with Fe. "Anthropogenically impacted" elements consist of Ag, Cd, Cu, Pb, and Zn. Vertical profiles show that TE contamination has increased dramatically after the IInd World War and reached a maximum between 1970 and 1980, consistently with anthropogenic atmospheric emissions changes. Sediment deposited on the Rhône prodelta at the beginning of XVIIth Century have 206/207Pb ratios close to values of natural Pb (1.200), whereas sediments deposited after 1850 AD are clearly contaminated by European gasoline and industrial Pb pools (<1.180). In addition, peak-events can be related to flooding periods, natural and man-induced channelization of the Rhône River mouth, or diagenetic processes. Highlights ► Trace elements are accumulated in the Rhône prodelta sediments. ► Preindustrial sediments recorded floods and channelization of the Rhône River. ► Contamination reached a maximum between 1970 and 1980 AD.